Pressure indicator

ABSTRACT

A pressure indicator comprising a piston which is displaceably mounted in a housing counter to the pressure of a spring on an axis and which can be impinged upon with pressure which is to be measured; also comprising optical display means actively cooperating with the piston. According to the invention, the structure of the indicator is simplified, compact and robust. This is achieved in that the optical display means comprise a front glass arranged perpendicular to the axis and one or several display elements which can be moved by the piston relative to said front glass and which respectively alternate at various pressures between a first position wherein they are optically visible from outside through the front glass and a second position wherein they are not optically visible from outside through the front glass.

TECHNICAL FIELD

The present invention relates to the field of the indication ofpressures which prevail in a volume filled with a medium, in particulara gas. It refers to a pressure indicator device according to thepreamble of claim 1.

Such a pressure indicator device is known, for example fromJP-A2-04145335.

PRIOR ART

Conventional pressure indicator devices (manometers) indicate thecurrent pressure in a volume filled with a medium, in particular gas,usually on a dial by means of a pointer rotatable about an axis ofrotation. The pressure is converted into a small rotational movement bymeans of a tube spring, capsule spring, plate spring or the like.However, manometers are also known. (JP-A2-04145335), in which, by meansof the pressure, a piston arranged in a cylinder is displaced counter tothe force of a spring and the displacement travel is converted into apointer rotation about the axis of displacement. Other manometers suchas are used, for example, for indicating tire pressures on a tire valve,indicate the displacement travel of the piston directly on a scaleextending in the direction of displacement (see, for example, U.S. Pat.No. 3,592,218).

In most manometers, a small movement caused by the pressure is steppedup mechanically, in order to obtain a clearly visible pointerdeflection. Pressure surges, mechanical vibrations or even knocks maydamage such instruments. If they are seriously damaged or even brokenaway, a hole appears which results in the emergence of the fluid or gas.The construction size does not allow such instruments to be used at allin instances where only a little space is available. On the other hand,comparatively high read-off accuracy is possible as a result of thelarge dial. In the direct indicators according to U.S. Pat. No.3,592,218, there is no step-up.

PRESENTATION OF THE INVENTION

The object of the invention is to provide a pressure indicator devicewhich allows an easily read-off optical indication of the pressure bythe simplest possible mechanical means, is extremely robust inmechanical terms, has a highly compact construction and can easily bemounted on a vessel which is under pressure.

The object is achieved by means of the whole of the features of claim 1.The essence of the invention is that the optical indicator meanscomprise a front glass arranged transversely to the axis and indicatorelements which are movable in relation to the front glass by means ofthe piston and which in each case change in the event of differentpressures between a first position, in which they are optically visiblefrom outside through the front glass, and a second position, in whichthey are optically not visible from outside through the front glass.

A first preferred embodiment of the pressure indicator device accordingto the invention is characterized in that the optical indicator meanscomprise a plunger displaceable toward the underside, acting as acontact face, of a front glass by means of the piston, the front glassand plunger being designed in such a way that they are at a differentdistance from one another at different locations in a planeperpendicular to the axis. As a result, when the piston is displaced, anoptically active contact between plunger and front glass is made atdifferent locations, depending on the piston position, and causes thecontact points to become visible through the, for example, matt frontglass. If the contact points are in the form of characters, inparticular digits or numerals, then, depending on the pressure on thepiston, different characters (for example, bars or the like arranged ina radiating manner on a circular ring) thus become visible insuccession.

A preferred development of this embodiment is distinguished in that thefront glass has a plane contact face, and that raised characters ofdifferent height are formed on that surface of the plunger which islocated opposite the contact face. The advantage of this is that asimple plane glass pane can be used as the front glass. Preferably, inthis case, the plunger consists of an elastomeric material, inparticular rubber.

It is also conceivable, however, that the plunger consists of a hardinelastic material, in particular of a plastic or a metal, and in thatthe interspace between the plunger and the front glass is filled with adisplaceable contrast medium.

Another preferred development is distinguished in that that surface ofthe plunger which is located opposite the contact face is plane, andthat raised characters of different heights are formed in the contactface of the front glass.

A second preferred embodiment of the pressure indicator device accordingto the invention is characterized in that the optical indicator meanscomprise a pointer spring engaged with the piston and having a pluralityof pointers, in that the pointer spring is designed in such a way that,during the pressure-induced displacement of the piston in the axialdirection and during the associated bending of the pointer spring, thepointers move transversely to the axis, in particular in the radialdirection, and in that, on the front glass, optical masking means areprovided, through which the pointers are visible or not visible throughthe front glass from outside, depending on the pressure.

In particular, the pointer spring is of disk-shaped design, the pointerspring being supported with its outer margin on a stop spring arrangedabove it and fastened to the housing and being acted upon in the centralregion by the piston, and the pointers extending upward in the axialdirection, being bent transversely to the axial direction at the upperend and having pointer heads of different lengths in the bent region,and the masking means comprising a circular printed face which isarranged on the underside of the front glass and which optically masksthe pointer heads when the pressure indicator device is in thepressureless state.

The pressure indicator device according to the invention can be used ina particularly versatile and simple way when it has the externalconfiguration of a screw with a head part and with a threaded part, andwhen the optical indicator means are arranged in the head part and thepiston is arranged in the threaded part.

In such a compact pressure indicator device, safety and capabilityduring use under rough conditions can be further increased when apredetermined breaking point is provided between the head part and thethreaded part in the housing, when the piston is sealed off below thepredetermined breaking point by means of a seal, and when a pressureplate for distributing the piston pressure is arranged between the upperend of the piston and the plunger or the pointer spring.

Further embodiments may be gathered from the dependent claims.

BRIEF EXPLANATION OF THE FIGURE

The invention will be explained in more detail below with reference toexemplary embodiments, in conjunction with the drawing in which:

FIG. 1 shows a longitudinal section through a first preferred exemplaryembodiment of a pressure indicator device according to the inventionwith an elastomeric plunger;

FIG. 2. shows a longitudinal section through a second preferredexemplary embodiment of a pressure indicators device according to theinvention: with a pointer spring; and

FIG. 3 shows a top plan view of the exemplary embodiment from FIG. 2 inthe case of low or absent pressure (FIG. 3 a; pointer heads are masked)and in the case of high pressure (FIG. 3 b; pointer heads emerge frombehind the mask).

EMBODIMENTS OF THE INVENTION

The first exemplary embodiment, illustrated in FIG. 1, shows a pressureindicator device (pressure indicator) 10 which comprises a one-piecehousing (monobloc) 18.

The housing 18 has the external form of a screw with a screw axis 26 andwith a head part (screw head) 28 and a threaded part 29. The housing 18has in the head part 28 corresponding key faces 15 on the outercircumference. In the low region of the housing 18, the threaded part29, a screw-in thread 22 is arranged coaxially to the axis 26, by meansof which screw-in thread the pressure indicator device 10 can be screwedpreferably into a cock attached to a compressed gas bottle. A piston 21with a head plate 25 is guided in the direction of the axis 26 withinthe housing portion provided with the screw-in thread 22. The head plate25 faces the pressure side. A spring 20, which is supported at the lowerend on the head plate 25 and at the upper end on the housing 18, actscounter to the piston 21, which is under pressure, and determines theaxial travel of the latter.

In order to prevent an emergence of gas between the piston 21 andhousing 18, an annular seal 19, preferably in the form of an O-ring, isinstalled. The end of the screw-in part of the housing 18 receives asolid cover 23 with a small damping bore 24 which limits the gasthroughflow. This form of construction prevents the situation where gasmay emerge if the upper part of the pressure indicator 10, whichcorresponds to the screw head, is damaged or even broken away. Apredetermined breaking point 11 in the middle region of the housing 18between the head part 28 and the threaded part 29 is intended, if thebottle falls down or the like, to make it easier for a break to occur atthe correct point, without the threaded part having the screw-in thread22 being torn out of the corresponding threaded bore of the cock. Thepiston 21 terminates level with the predetermined breaking point 11 andis therefore not put at risk in the event that the housing 18 breaksaway at the predetermined breaking point 11.

Located in the upper portion of the pressure indicator 10 is a pressureplate 16 which is acted upon by the piston 21 and which presses aplunger 14, arranged above it, toward the underside, acting as a contactface 13, of a matt front glass 12 which closes off the housing 18upwardly. The plunger 14 consisting of an elastically deformablematerial, for example rubber, is fixed at a margin between the frontglass 12 and the housing 18 and in the inner region carries arranged soas to be distributed on the top side, characters 27 formed withdifferent heights. The matt front glass 12 prevents the characters(digits, letters or the like) of unequal height from being directlyvisible from above when the pressure indicator 10 is viewed on top. If,then, the piston 21 is pressed upward (outward) by the gas pressure, thepressure plate 16 is pushed, together with the plunger 14, toward thematt side of the front glass 12. Due to the contact of the preferablydark-colored rubber or rubber-like plunger with the bright matt surfaceof the front glass 12, the highest of the characters 27 is the first tobecome visible from outside. The height gradations of the characters 27on the plunger 14 correspond to the stroke which the piston 21 executesin the event of increasing pressure. When the compressed gas bottle isfull, all the characters 27 are pressed against the matt front glass 12.The characters are “extinguished” in series in the event of fallingpressure, in a similar way to an LCD (Liquid Crystal Display) indicator.

For practical reasons, the indicator, that is to say the arrangement ofthe characters 27 on the top side of the plunger 14, is configured insuch a way that it does not appear in any position after being tightenedfirmly when being mounted on the head. In another embodiment (notillustrated in FIG. 1), instead of the plunger 14 with the raisedcharacters 27, a flat plunger is installed. In the pressureless state,the plunger, remains back from the front glass and does not make anycontact. In this embodiment, the front glass, injection-molded fromplastic, carries the characters projecting inward. There is thepossibility, here, of lettering on the inside of the front glass. Theremaining functioning is identical to that of the first embodiment.

A further embodiment is distinguished in that the space between thesmooth front glass 12 and the plunger 14 is filled with a contrastmedium. The plunger 14 or a comparable indicator means therefore nolonger has to be soft and elastic. They can be manufactured from harderplastic or from metal. In the pressureless state, the plunger 14 is notvisible on account of the contrast medium. When it is pressed againstthe front glass 12 by the pressure in the bottle, the interposedcontrast medium is displaced, and the contour of the character 27 on theplunger 14 becomes visible.

In this respect, however, even an indication which is as it werecontinuous is possible: If, for example, an elastomeric plunger 14 isused, which does not carry any special characters 27, but is designedupwardly in conical form or in the form of a spherical cap, the plungeris pressed to a greater or lesser extent onto the matt front glass 12,depending on the pressure, and is thus compressed. The indication whichappears is a filled-out circle with a greater or lesser diameter, thediameter changing continuously with the pressure. It goes without sayingthat, in this refinement, scale circles corresponding to a specificpressure value may be formed on the front glass 12.

FIG. 2 illustrates in longitudinal section a second preferred exemplaryembodiment of the invention. The pressure indicator device 10′ of. FIG.2 is identical in most parts to the example of FIG. 1, and therefore thesame reference symbols are used for these parts. Instead of the plunger14 from FIG. 1, a special pointer spring 32 is installed here. The(disk-shaped) pointer spring 32 sits on a pressure plate 16 b andengages with its outer margin behind a stop ring 30 fastened to thehousing 18. Said pointer spring carries, on its circumference, a numberof pointers 34 which extend upward and are bent at the upper end andwhich have pointer heads 33 of unequal length which have a high contrastwith respect to an (opaque) printed face 31 on the underside of thefront glass 12. In a state free of pressure, the pointer spring 32 is inthe position of rest. All the pointer heads 33 are located behind theround printed face 31 on the front glass, that is to say are masked bythis face and are therefore not visible (FIG. 3 a).

When the bottle is full, the pressure plate 16 b is pressed forward(upward) to the greatest possible extent. As a result, the pointerspring 32 bends in the region between the pressure plate 16 b and thestop ring 30. The result of this is that all the pointers 34 andconsequently all the pointer heads 33 move outward and, according totheir length, emerge successively behind the printed face 31 and therebybecome visible (FIG. 3 b). If the pressure in the bottle falls, thepressure plate 16 b moves away from the front glass 12. The bent regionbetween the pressure plate 16 b and the stop ring 30 can thereby bendback a little. The result of this is that the pointer 34 with theshortest pointer head 33 is the first to disappear under the printedface 31 of the front glass 12. The number of remaining pointer headsgives information as to the filling state of the bottle. In the printingof the front glass 12, a labeling can be inserted in a simple way, whichcan give further information as to the gas in the bottle.

Manufacturer's imprints may also be made. In a pressure indicator ofthis construction type, it is possible to ensure an even finersubdivision of the indicator. Moreover, maximum indication contrast ispossible. The example according to FIG. 2 is therefore distinguished bythe following features:

-   -   The correct design of the pointer spring 32 achieves a step-up        which results in a large deflection of the pointer head 33,        without further parts being necessary.    -   A change in the step-up, is achieved in a simple way by the        diameter of the pressure plate 16 b being varied.

Overall, in instances where no particular accuracy is demanded, theinvention affords a novel and particularly advantageous possibility forpressure indication: the pressure indicator according to the inventionis in the manner of a screw. It consequently becomes possible toindicate the pressure of a gas bottle constantly. The pressure indicatoris screwed directly into an additional bore laterally on the cock. Thehard-wearing capacity of the indicator far exceeds all manometers knownhitherto, even that of the cock into which it is screwed. Even thefailure or breaking away of the above mentioned part does not cause anyaccident or any leak. At the same time, the size is dimensioned (with alength of, for example, 20 mm and with a maximum diameter of, forexample, 19.5 mm, this corresponding to a screw head with the key widthof 17 mm) such that a protective cap, which, according to regulations,protects the cock, can continue to be used. In bottles with valves whichdo not have to be protected by protective caps for transport purposes,an even greater advantage is afforded in that the pressure in the bottleis visible at a glance without manipulations. Logistical problems areconsequently solved. The construction is very simple, so that, while thehigh degree of safety remains unchanged, costs can be saved.

Since no step-up or other awkward parts are required, the pressureindicator 10 according to the invention is very hard-wearing. Theinstallation of the piston 21 with a head plate 25 prevents a damaged orbroken-away upper part from causing leaks and accidents. The use of aplunger 14 with “lettering” of unequal height or of a pointer spring 32with pointer heads 33 of different lengths leads to a very simplemonobloc housing (18) which at both ends receives a “cover” (cover 23and front glass 12) which is rolled in or crimped in. For protection inthe event of a leak of the seal 19, the pressure indicator is providedwith a pressure equalizing or safety bore 17. The front glass 12 is thusprotected from excess pressure.

List of Reference Symbols

-   10, 10′ Pressure indicator device (pressure indicator)-   11 Predetermined breaking point-   12 Front glass-   13 Contact face-   14 Plunger-   15 Key face-   16, 16 b Pressure plate-   17 Pressure equalizing bore-   18 Housing (one-piece)-   19 Seal-   20 Spring-   21 Piston-   22 Screw-in thread-   23 Cover-   24 Damping bore-   25 Head plate-   26 Axis-   27 Character (digits, letters, etc.)-   28 Head part-   29 Threaded part-   30 Stop ring-   31 Printed face-   32 Pointer spring-   33 Pointer head-   34 Pointer

1-13. (cancelled)
 14. A pressure indicator device comprising a piston,mounted displaceably in a housing along an axis counter to a pressure ofa spring and configured to be acted upon by a pressure to be measured,and optical indicator means operatively connected to the piston, whereinthe optical indicator means comprise a front glass arranged transverselyto the axis and one or more indicator elements are movable in relationto the front glass by means of the piston, and wherein the indicatorelements move between a first position and a second position in theevent of different pressures, wherein the indicator elements areoptically visible from outside through the front glass when they are inthe first position, and wherein the indicator elements are optically notvisible from outside through the front glass when they are in the secondposition.
 15. The pressure indicator device as claimed in claim 14,wherein the optical indicator means comprise a plunger displaceabletoward the underside, acting as a contact face, of a front glass bymeans of the piston, the front glass and plunger configured so that theyare at a different distance from one another at different locations in aplane perpendicular to the axis.
 16. The pressure indicator device asclaimed in claim 15, wherein the front glass has a plain contact face,and wherein raised characters of different heights are formed asindicator elements on that surface of the plunger which is locatedopposite the contact face.
 17. The pressure indicator device as claimedin claim 16, wherein the plunger consists of an elastomeric material.18. The pressure indicator device as claimed in claim 16, wherein theplunger consists of a hard inelastic material, and wherein an interspacebetween the plunger and the front glass is filled with a displaceablecontrast medium.
 19. The pressure indicator device as claimed in claim15, wherein the surface of the plunger which is located opposite thecontact face is plain, and wherein raised characters of differentheights are formed in the contact face of the front glass.
 20. Thepressure indicator device as claimed in claim 14, wherein the opticalindicator means comprise a pointer spring engaged with the piston andhaving a plurality of pointers, wherein the pointer spring is configuredso that when, during the pressure-induced displacement of the piston inan axial direction and during an associated bending of the pointerspring, the pointers move transversely to the axis in a radialdirection, and wherein optical masking means are provided on the frontglass through which the pointers are one of visible and not visiblethrough the front glass from outside, depending on the pressure.
 21. Thepressure indicator device as claimed in claim 20, wherein the pointerspring is of disk-shaped design, wherein the pointer spring is supportedwith its outer margin on a stop ring arranged above it and fastened tothe housing and is acted upon in a central region by the piston, whereinthe pointers extend upward in the axial direction, are bent transverselyto the axial direction at the upper end and have pointer heads ofdifferent lengths in the bent region, and wherein the masking meanscomprise a circular printed face, wherein the masking means is arrangedon the underside of the front glass, and wherein the masking meansoptically mask the pointer heads when the pressure indicator device isin a pressureless state.
 22. The pressure indicator device as claimed inclaim 14, wherein the pressure indicator device includes a screw with ahead part and a threaded part, and wherein the optical indicator meansare arranged in the head part and the piston is arranged in the threadedpart.
 23. The pressure indicator device as claimed in claim 22, whereina predetermined breaking point is provided between the head part and thethreaded part in the housing, wherein the piston is sealed off below thepredetermined breaking point by a seal, and wherein a pressure plate fordistributing the piston pressure is arranged between the upper end ofthe piston and one of the plunger and the pointer spring.
 24. Thepressure indicator device as claimed in claim 14, wherein the housing isin one piece and is closed off in the head part outwardly by the frontglass, and wherein a pressure equalizing bore leads outward between thefront glass and the threaded part in the housing.
 25. The pressureindicator device as claimed in claim 14, wherein the housing is in onepiece and is closed off in the threaded part outwardly by a cover, andwherein a damping bore leading outward is provided in the cover.
 26. Thepressure indicator device as claimed in claim 24, wherein the frontglass and the cover are one of rolled and crimped into the housing. 27.The pressure indicator device as claimed in claim 15, wherein thepressure indicator device includes a screw with a head part and athreaded part, and wherein the optical indicator means are arranged inthe head part and the piston is arranged in the threaded part.
 28. Thepressure indicator device as claimed in claim 20, wherein the pressureindicator device includes a screw with a head part and a threaded part,and wherein the optical indicator means are arranged in the head partand the piston is arranged in the threaded part.
 29. The pressureindicator device as claimed in claim 15, wherein the housing is in onepiece and is closed off in the head part outwardly by the front glass,and wherein a pressure equalizing bore leads outward between the frontglass and the threaded part in the housing.
 30. The pressure indicatordevice as claimed in claim 20, wherein the housing is in one piece andis closed off in the head part outwardly by the front glass, and whereina pressure equalizing bore leads outward between the front glass and thethreaded part in the housing.
 31. The pressure indicator device asclaimed in claim 15, wherein the housing is in one piece and is closedoff in the threaded part outwardly by a cover, and wherein a dampingbore leading outward is provided in the cover.
 32. The pressureindicator device as claimed in claim 20, wherein the housing is in onepiece and is closed off in the threaded part outwardly by a cover, andwherein a damping bore leading outward is provided in the cover.
 33. Thepressure indicator device as claimed in claim 25, wherein the frontglass and the cover are one of rolled and crimped into the housing.